Improved removal of soils and stains is a constant aim for laundry detergent manufacturers. In spite of the use of many effective surfactants and polymers, and combinations thereof, many surfactant-based products still do not achieve complete removal of greasy/oily stains, colored stains and particulate soils, especially when used at low water temperatures.
Fabric, especially clothing, can become soiled with a variety of foreign substances ranging from hydrophobic stains (grease, oil) to hydrophilic stains (clay). The level of cleaning which is necessary to remove these foreign substances depends to a large degree upon the amount of stain present and the degree to which the foreign substance has contacted the fabric fibers. For example, grass stains usually involve direct abrasive contact with vegetative matter thereby producing highly penetrating stains. Many cleaning formulations use combinations of enzymes to aid in the peptization and removal of these stains. Alternatively, clay soil stains, although in some instances contacting the fabric fibers with less force, nevertheless provide a different type of soil removal problem due to the high degree of charge associated with the clay itself. This high surface charge density resists any appreciable peptization and dispersal of the clay by conventional surfactants and enzymes. For these soils, peptizing polymers and builders aid in the removal of the soils. Finally, hydrophobic stains, such as greases and oils, usually involve another soil removal problem since technologies that remove grass stains and outdoor soil stains (clay) do not effectively aid in grease removal. For these hydrophobic stains, a surfactant or combination of surfactants is generally preferred for removal. For these reasons, an effective cleaning formulation is typically comprised of many technologies that aid in removal of a variety of soils. Unfortunately, due to cost and formulation constraints, it is rare to find a cleaning formulation that effectively incorporates each of the above cleaning technologies to completely remove all of the target soils and stains on fabrics or textiles.
Conventional soil release polymers are generally effective on polyester or other synthetic fabrics where the grease, oil or similar hydrophobic stains spread out and form an attached film and thereby are not easily removed in an aqueous laundering process. Many conventional soil release polymers have a less dramatic effect on “blended” fabrics, that is, on fabrics that comprise a mixture of cotton and synthetic material; and have little or no effect on cotton articles. One reason for the affinity of many soil release agents for synthetic fabric may be that the backbone of a conventional polyester soil release polymer typically comprises a mixture of terephthalate residues and ethyleneoxy or propyleneoxy polymeric units; the same materials that comprise the polyester fibers of certain synthetic fabric. This similar structure of soil release agents and synthetic fabric may produce an intrinsic affinity between these compounds.
There is a long felt need in the art for laundry detergent or fabric care compositions that contain soil release polymers (“SRP”), including polymers from natural renewable resources, that can effectively modify the fabric surface, such as cotton fabrics, to aid in the removal of many types of both hydrophilic and hydrophobic soils from fabric. In addition, as the effectiveness of the SRP increases there is less of a burden on the other cleaning technologies so that one could formulate the compositions using less of these other materials, use more cost effective materials and/or leverage improved cleaning to drive consumer noticeability.